1. Field of the Invention
The present invention relates to a wet type friction member which is used in a wet type multiplate clutch, a single plate clutch of a wet type friction brake, a synchronizer ring, a lock up clutch or the like for a vehicle and an industrial or construction vehicle or the like and a manufacturing method for the same.
2. Description of the Related Art
FIG. 1 is a sectional view showing a basic constitution of a wet type multiplate clutch 10 using a wet type friction member. Numeral 1 designates a clutch case. Numeral 11 designates a spline groove. Numeral 21 designates a separator plate spline-engaged with the spline groove 11. Numeral 22 designates a friction plate. Numeral 3 designates a press plate. Numeral 5 designates a stop ring and the friction plate 22 is spline-engaged with a hub (not illustrated) which corresponds a counter member of transmitting rotation from the clutch case 1. A transmitting member 2 is formed by the separator plate 21, the friction plate 22, the press plate 3 and the like.
Numeral 4 designates a piston. In fastening the clutch, when pressurized oil is introduced from a pressurized oil hole 61 to a hydraulic operating chamber 6, a rotational force is transmitted by pressing the piston 4 in a right direction and pressing the transmitting member 2 to the stop ring 5. In releasing the clutch, when the pressurized oil is drawn from the hydraulic operating chamber 6, the piston 4 returns in a left direction by a return spring 7. At this occasion, the oil is brought into a canceller 8 from an oil hole 81 to strengthen to return the piston 4 by a centrifugal force thereof.
FIG. 2 is a front view taking out to show the friction plate 22, and a friction member 25 is pasted to a core plate portion 23 of a metal. Numeral 24 designates spline teeth provided at an inner periphery of the core plate.
As a wet type friction member, in a conventional, a so-called paper friction member in which paper is used as a base material has mainly been used. The paper friction member is fabricated by blending various friction conditioners to pulp, making paper from the pulp, and impregnating and curing a binding resin such as phenol resin or the like. Up to a current state, the conventional paper friction member can be regarded to show excellent functions to substantially meet requests of heat resistance, μ-V characteristic, wear resistance between layers and the like. Further, notation μ, mentioned above, designates a friction coefficient, and notation V designates a speed of sliding with a counter member. As the μ-V characteristic, it is regarded to be preferable to provide a positive gradient property in which in accordance with an increase in V, also μ is increased.
Although the conventional paper friction member provides with considerably excellent functions, however under a current condition of increasing a load on the wet type friction member by increasing an output of an engine of a vehicle, it becomes difficult to simultaneously ensure functions to be satisfied of the heat resistance, the μ-V characteristic, the wear resistance between layers and the like.
The paper friction member is formed with pores by intertwining fiber. Although, when the porosity is increased, the heat resistance is improved, however the wear resistance between layers (shear strength) is decreased. Conversely, although when the porosity is decreased, the wear resistance between layers is increased, the heat resistance is deteriorated. The both are brought into a trade off relationship. In this way, a change in an environment of use cannot be dealt with by the paper friction member.